Modulation of intein activity by its neighboring extein substrates.

Inteins comprise a large family of phylogenetically widespread self-splicing protein catalysts that colonize diverse host proteins. The evolutionary and functional relationship between the intein and the split-host protein, the exteins, is largely unknown. To probe an association, we developed an in vivo and in vitro intein assay based on FRET.

Zinc finger as distance determinant in the flexible linker of intron endonuclease I-TevI.

I-TevI, the phage T4 td intron-encoded endonuclease, recognizes a lengthy DNA target and initiates intron mobility by introducing a double-strand break in the homing site. The enzyme uses both sequence and distance determinants to cleave the DNA 23-25 bp upstream of the intron insertion site. I-TevI consists of an N-terminal catalytic domain and a C-terminal DNA-binding domain separated by a long, flexible linker.